In prior art keyphone systems, when users frequently call for business or conduct their business in conference with one another, they are required to interrupt other extension subscribers' calls because the line is busy for a long time or it is necessary for users to dial whenever assistance for business arises.
As stated above, when the users must frequently call for business, the prior art keyphone systems provide the users with inconvenience to dial one by one whenever to call as well as to interrupt the other extension subscribers' calls because the line is busy for a long time.
U.S. Pat. No. 5,260,986 for a Group Notification Service and System to Pershan discloses a method of using a public switched telecommunications network to deliver to designated persons a message. U.S. Pat. No 5,544,237 for an Automatic Conference Initiation Upon All Telephones for the Conference being Idle to Bales et al. Discloses telephone terminals that initiate the conference feature. U.S. Pat. No. 5,153,908 for an Automatic Redial in a Key Telephone System Having Different Line Types to Kakizawa et al. Discloses idle outside lines selected and acquired in accordance with the order of preference.
What is needed is a method for automatically calling telephones in a telephone system. The extension number of the telephone to be called is stored in a register and then automatically called.